THE ACID BESSEMER PKOCESS. 105 manganese in the pig. Table VI-B gives analyses of metals and slags at different periods of the operation. It will be seen that when manganese is present in large proportion, quite an amount is left in the steel after the boil has begun and even after most of the carbon has been eliminated. This will be illustrated by Table YI-CL TABLE VI-C. Steel from High-Manganese Pig-iron. Pig-Iron with 4 per cent. Mn and 1 per cent. SI. Element. Composition, per cent., of various heats. 0 .... Mn . . . Si .... 1.8 0.6 0.06 1.1 0.65 0.05 0.9 0.5 0.045 0.7 0.4 0.045 0.5 0.3 0.04 0.8 0.2 0.03 0.2 0.15 0.02 0.15 0.12 0.016 Pig-Iron with 5 to « per cent. Mn and 1 per cent. Si. Element. Composition, per cent., of various heats. 0 .... Mn . . . Si .... 1.3 1.25 0.25 1.1 1.05 0.2 0.9 0.9 0.15 0.7. 0.7 0.12 0.0 0.6 0.1 SEC. Vie.—History of the slag.—Akerman discusses the part which the slag plays in the oxidation of the metalloids, but I have ventured to disagree with him on this point* In the open-hearth process, the history of the slag is the history of the operation, for all the changes in the composition of the metal must be done through the mediation of the slag, but in the Bessemer the blast enters from the bottom and passes upward through the metal before it ever comes in contact with the slag. It is true that the charge is in a state of violent ebullition and that the slag is carried down into the metal, but such a mixing does not seem to be a necessary part of the operation, for, when the heat is first turned up, the silicon is immediately oxidized, although no slag is present. In short, the question resolves itself into a reductio ad absurdum, for it is the oxidation of the silicon which creates the slag, and hence the slag can hardly be necessary for the oxidation of silicon.' The slag does automatically adjust its own composition, and will do so * Trans. A. I. M. Jff., Yol. XXII, p. 667.